Patent GB-539617-A (GB)
Title: Improvements relating to railway-traffic controlling apparatus
IPC: B61L19/06
Filed: 1939-11-01
Abstract: 539,617. Railway signalling systems; electric switches. TOMLINSON, A. V. (Union Switch & Signal Co.). Nov. 1, 1939, No. 29115. [Class 105] [Also in Group XXXVII] In a railway traffic control system a selected route is set up by a manually-operable rotary selector switch which can also be pushed or pulled, such switch devices being arranged on a mimic diagram of the layout and each selectively controlling route relays for a number of routes having a common entrance. Each device also has auxiliary non-selective contacts controlling the circuit of an auxiliary stick relay a front contact of which is included in the energizing circuit of each route relay controlled by the device. As described the switch comprises a shaft b slidably and rotatably mounted in the diagram panel a and rear panel c on which pairs of blade contacts (one pair only shown at c<SP>6</SP>) are arranged concentrically about the shaft, one pair for each route controlled by the switch. The shaft has an operating knob e, pointer f, disc g, radial contact arm d and is biased to an axial midposition from which it can be moved by pushing or pulling knob e. The edge of disc g is engaged by a slots h in a pair of bell-crank levers i (one shown) pivoted at j so that the levers are not affected by rotation of the shaft but are rocked by its axial movement. The other arms co-operate with two sets of movable contacts mounted on panel c. One set comprises a movable contact k co-operating with fixed contacts k<SP>1</SP>, k<SP>2</SP> contacts k, k<SP>1</SP> being normally closed and contacts k, k<SP>2</SP> open. The other set, not shown, is similar except that the fixed contacts are normally both in contact with the movable contact. Fig. 5 illustrates a layout comprising two parallel tracks and sidings connected by a cross-over, with points 7, 8, 9 and signals 1 ... 6. The tracks are divided into insulated track-sections A2T, 2T, B2T, A5T, 5T, B5T, with the usual track relays not shown. The Specification gives separate diagrams of the circuits for the auxiliary stick relays, route relays, pointreversing relays, point control relays, and signal relays for the layout shown and traces in detail the operation of setting up the route 1-6. In general, a route-setting operation is as follows. Knob e is rotated to a position, indicated by pointer f, corresponding to the desired route and is then pressed in to engage contact arm d between the selected pair of contacts such as c<SP>6</SP> and to close contacts k, k<SP>2</SP>. Contacts k, k<SP>2</SP> close the energizing circuit of the auxiliary relay associated with the operated switch device, and common to all the routes controlled thereby. A front contact of the auxiliary relay then closes the auxiliary relay stick circuit over the second set of normally closed lever-controlled contacts referred to above, in series with track-relay contacts so that the auxiliary relay remains energized until a train enters the appropriate track section or button e is pulled to cancel the route. A front contact of the auxiliary relay closes the circuit of the selected route relay over the selected contacts such as c whilst the arm d is still engaged between them. The energizing circuits of the auxiliary and route relays also include interlocking contacts to prevent conflicting operations, such contacts as affect equally each of the routes controlled by the selector switch being preferably included in the auxiliary relay circuit to save their repetition in each of the route relay circuits. The auxiliary relay pick-up circuit associated with each switch device (but not its stick circuit), also includes in series the normally closed contacts k, k<SP>1</SP> of other switch devices (but not its own k, k<SP>1</SP> contacts). This prevents simultaneous effective operation of two devices, as the pressing inwards of a knob e to close its contacts k, k<SP>2</SP> simultaneously breaks the pick-up circuit of any other auxiliary relay in which its contacts k, k<SP>1</SP> are included. When the selected route relay is energized, a front contact thereof bridges the selecting contacts such as c<SP>6</SP> to maintain the route relay energized after return of'arm d to normal position. Front contacts of the route relay or of the auxiliary relay close circuits of the involved point reversing relays, front contacts of which, in series with locking relay contacts controlled by track occupation or approach conditions in known manner, close the point relay circuits. Signal relays are then closed over front contacts of the point relays and the auxiliary relay, the latter ensuring return to " danger " when the auxiliary relay is de-energized. The circuit also includes contacts of specified timing, checking, and other relays. In the system described, the circuit of a point reversing relay, when each route issuing from the point location involves reverse position of the corresponding points, as with points 7 in the route 1-6 described, is closed by a front contact of the auxiliary relay, the reversing relay circuits of other points to be reversed for the selected route being closed by front contact of the route relay. Also, whilst locking relays are provided for points 7, 9, their front contacts being included in the corresponding point relay circuits, provision of a separate locking relay for points 8 is avoided by including in series in the points relay circuits for these points front contacts of both locking relays of points 7, 9, one or other of these contacts being effective when locking of points 8 is necessary.